%/** 
%Focus-vector computation 
%@param alpha - elevation, scalar, rad 
%@param beta - azimuth, scalar, rad 
%@return H - focus-vector 
% relevant to antenna's center, 4x1, rad 
%*/ 
function Hv = H( alpha, beta )
 k = [cos(alpha)*cos(beta); % Unit vector 
 cos(alpha)*sin(beta); 
 sin(alpha)]; 
 
 r{1} = [0 0 0]; % Antenna's radius-vector, lambdas 
 r{2} = [1 0 0]; 
 r{3} = [1/2 -sqrt(3)/2 0]; 
 r{4} = [-1/2 -sqrt(3)/2 0]; 
 r{5} = [-1 0 0]; 
 r{6} = [-1/2 sqrt(3)/2 0]; 
 r{7} = [1/2 sqrt(3)/2 0];
 
 phi = nan(7,1); 
 
 for i = 1:7 
 phi(i) = 2*pi * r{i} * k; 
 end 
 Hv = exp( 1i * phi ); 
end
